A bone screw having a tubular wall with a plurality of recesses is described in DE 100 55 891 A1. It includes a thread section, a tip at one end and a head for engagement with a screwdriver at the other end. The thread section of the tubular wall also comprises the plurality of recesses.
This bone screw can be used e.g. in the treatment of osteoporotic fractures. On account of the open mesh (or net-like) design of the screw, fusion with surrounding bone material can take place.
A problem can be encountered when the position of the fracture in the bone, which e.g. in the hipbone is far away from the surface from which the screw is screwed in. In such situation, for reliable fixation, precise positioning of the bone screw is required and, sometimes, a mechanical connection to external and/or internal bracing implants also may be required.
A bone screw system including a cannulated bone screw and an adapter designed to be releasably coupled to the screw is known from U.S. Pat. No. 6,048,343. The bone screw has a head with a diameter which is larger than the diameter of the shaft of the screw. The largest diameter of the adapter is also greater than the diameter of the shaft of the bone screw. Thus the bone screw cannot be placed at a fracture which is at a location far away from the surface of the bone. DE 199 49 285 A1 discloses a similar bone screw system including a bone screw and an adapter.